Grinding machine



Jan. 23, 1945. DECKER ETAL 2,367,759

GRINDING MACHINE Filed Aug. 13, 1942 6 Sheets-Sheet 1 INVENTORS.

Jan. 23, 1945. J. DECKER ET AL 5 5 GRINDING MACHINE Filed Aug. 15, 1942a Sheets-Sheet 2 Jan 23, 194-5. DECKER ETAL 2,367,759

- GRINDING MACHINE Filed Aug. 13, 1942 6 Sheets-Sheet 5 mill-lull A770NEX Jan. 23, 1945. J. DECKER ETAL 2,367,759

GRI NDING MACHINE Filed Aug. 13, 1942 6 Sheets-Sheet 4 Jan. 23, 1945.

Filed Aug. 15, 1942 6 Sheets-:Sheet 5 Jan. 23, 1945. J. DECKER ET ALGRINDING MACHINE 6 Sheetg-Sheet 6 Filed Aug. 13, 1942 INVENTORS. J4co5pfC/Tf? fiafp/i-Kfiaamy BY M W/W.

Patented Jan. 23, 1945 GRINDING MACHINE Jacob Decker, Cincinnati, andAlbert D. C. Stuckey, Hamilton, Ohio, assignors to The CincinnatiMilling' Machine Co., Cincinnati, Ohio, a corporation of OhioApplication August 13, 1942, Serial No. 454,682

17 Claims.

This invention relates to grinding machines and more particularly to animproved automatic infeeding mechanism for the grinding wheels of suchmachines.

One of the objects of this invention is to provide an improved automaticinfeeding mechanism for controlling the movement between a grindingwheel and a work piece in such a manner that the grinding wheel willexecute a complete cycle of rapid advancing to the work, moving at aslow feed rate to grind the work to size and of automatically returningto its starting position.

Another object of this invention is to provide improved hydro-mechanicaltransmission for executing infeed cycles in which the actuating force ishydraulic and the controlling force is mechanical. Y

A further object of this invention is to provide an improved poweroperated infeed mechanism which is suitably interlocked with the tabletraverse mechanism so that inadvertent power or manual movement of thetable is prevented during operation of the cycle.

Other objects and advantages of the present invention should be readilyapparent by reference to the following specification, considered inconjunction with the accompanying drawings forming a part thereof and itis to be understood that any modifications may be mad in the exactstructural details there shown and described, within the scope of theappended claims, Without departing from or exceeding the spirit of theinvention.

Referring to the drawings in which like reference numerals indicate likeor similar parts:

Figure 1 is a front elevation of a grinding machine embodying theprinciples of this invention.

Figure 2 is a, vertical section through the machine shown in Figure lwith suitable parts broken away to show the mechanical part of thetransmission for feeding the grinding wheel.

. Figure 3 is a vertical section through the machine as viewed on theline 33 of Figure 1 showing the table traversing mechanism.

Figure 4 is a detail section on the line 4-4 of Figure 1.

Figure 5 is a diagrammatic View of part of the hydraulic controlcircuit.

Figure 6 is a diagrammatic view of the remainder of the hydrauliccontrol circuit and more particularly the table control mechanism.

Figure '7 is a section on the line 1-1 of Fig ure 2.

Figure 8 is a section on the line 8-8of Figure-7.

Figure 9 is an enlarged detail view of amultiple position stop fordetermining the angularity of th feed rate control cam.

Referring to Figure 1 of the drawings thereierence numeral 10 indicatesthe bed of a grinding machine embodying the principles of thisinvention. The upper part of the front of the bed is provided with apair of guideways II and I2 as more particularly shown in Figure 3 forree ceiving and guiding a work table l3 which is .utilized fortraversing a work piece relative tolthe grinding wheel l4 shown inFigures 1 and,2,. The grinding. wheel is suitably supported for re}tation on the wheel slide l5 and conventional means. not shown arecarried by the slide for driving the grinding wheel. v

The table [3 is actuated by a hydraulic motor in the form of a cylinderl5 and a piston it, Figure 6, the piston being connected by a piston rodI! to the table I3. The admittance and exhaust of fluid pressure to thecylinder l5 iscon trolled by a table control valve, various sectionsthrough which are indicated by the reference numerals l8, I9, 20 and 2|in Figure 6 of the drawings. This valve has a rotatable plunger 23 towhich the control lever 24, shown in Figure l, is operatively connectedthrough gearing 24', whereby the lever rotates in an opposite directionto the valve plunger 23. This lever has a central or stop position whichis the position shownf,-'-a running position indicated by the dash 'and'do t line 25 which is to the left of the stop position, and a thirdposition indicated by the dash and dot line 26 which is to the right ofthe stop position and which is utilized to efiect automatic retractionof the grinding wheel.

The wheel head is provided with a cylinder -27, Figures 2 and 5, forreceiving a rack piston 28. A pinion 29 is secured to the upper end ofavertical shaft 30 in mesh with the rack portion 3| of the piston 28 andthe lower end of the shaft is provided with a worm wheel 32 whichintermeshes with a worm 3s. Attention isinvited to the fact that the shaft 30is journaled in the bed l0 and therefore isincapable of anyrelativebodily movement with respect to the bed'while" the rack piston iscapable of relative bodily movement with respect to the wheel head [5.

Also the worm 33 is supported for relative axial movement withrespect tothe bed I 0 by a piston 34 and a journal 35 which are formed integralwith opposite ends of theworm. The piston3 i slides, ina cylinder 36While the journal 3-5 is capable of rotation or axial movement relativeto the bearing 3? which is carried by the bed.

The piston and cylinder 21, 28 are utilized in effecting rapid traversemovement of the wheel head, while the axial movement of the worm 33 isutlized for effecting feeding movements of the wheel head. Rotation ofthe worm 33 -is utilized for effecting adjustment of the wheel headrelative to its actuating mechanism to change the final or sizedetermining position of the grinding wheel.

In an automatic infeed cycle of the grinding wheel, the wheel head isfirst advanced at a rapid traverse rate to bring the wheel up to thework. A feed rate is then instituted which causes the work to be groundto size and then after a slight dwell to allow the grinding wheel toclean up, automatic reversal takes place causing the wheel head to bereturned and stopped.

The hydraulic control circuit in Figure 5 has the various parts shown inthe position which they assume just prior to the automatic reversal. Inorder to more clearly understand how these movements are obtained letitbe assumed that the wheel head is in a retracted position. Since thecylinder 21 is divided into two portions the forward portion ofthezcylinder will be indicated by the reference numeral 38 and the rearportion of the cylinder will be indicated by the reference numeral 39.The piston portion which slides in the cyliner 38 will be indicated bythe reference numeral 40 and the piston portion which slides in thecylinder 39 will be indicated by the reference numeral 4!. When thewheel head is in a retracted position, fluid pressure has been connectedto the cylinder 39. Since the pinion 29 is held against rotation by itslocking connection with the worm 33, which in turn holds the rack piston28 and thereby the piston 4| against bodily movement, pressure incylinder 39 will force the slide l5 to the rear.

It must be remembered, however, that the forward end of the piston 40will engage the end of cylinder 38 to limit or stop the movement andthat once contact is established between. the piston 40 and the end ofcylinder 38, the rack pisten 28 and slide 15 may be considered as asingle entity so that torsional strain on the pinion 29 is immediatelyrelieved. Further, the pinion 29 may be rotated to effect bodilymovement of the wheel head IS in either direction and the onlyresistance is the friction of the slide.

It has been stated that the worm 33 was capable of axial movementrelative to the bed, but this movement is limited in extent and onlysufficient to effect the feed or stock removal operation. The cylinder36 is connected to a source of pressure at al times, and *since thecylinder is part of. the bed the piston 34, as well as the worm 33, areconstantly urged toward the right as viewed in Figure 2. Ananti-friction thrust bearing 42 is interposed between a shoulder 43formed on. the. end of the: journal 35, and a thrust plate 44' attachedto the staface recedes sufficiently at the end of its stroke to permitthe worm to engage the positive stop.

If any additional movement is necessary, the worm must be rotated by thehandwheel 46 which is connected through gearing 41 to the shaft 48. Theshaft 48 is connected to the piston rod 49 of piston 34 by a slidablejoint 50 which permits relative axial movement between the shaft 48 andthe rod 49,

It will thus be seen that the rack 28 is normally locked with the wheelhead and that the worm 33 is locked between the cam 45 and the hydraulicpressure acting on the piston 34 so that during rotation of the handwheel the effect is the same as if no sliding connections existedbetween the various parts and the wheel head may be adjusted in eitherdirection. Such adjustment changes the zone of operation of the grindingwheel as for different sizes of work without changing the length of itsrapid traverse or feed movements.

'I'o effect automatic operation of the wheelhead, fluid pressure isadmitted to the forward cylinder 38 and the rear cylinder 39 isconnected to exhaust whereby the fluid pressure reacts against thepiston which is held against movement by the pressure in cylinder 36.The wheel head advances relative to the rack piston 23 until it hits therear end of piston 41 whereby it is positively stopped and once againthe piston and the wheel head become a single unit. Further advancing iseffected at a feeding rate by moving the cam in the direction of arrow5| as viewed in Figure 5, thereby causing the face of the cam to recedewhereby the fluid pressure in cylinder 36 will urge the worm 33 towardthe right and cause movement of the wheel head through the rack piston28 toward the left, all as viewed in Figure 5, thereby feeding thegrinding wheel l4 toward the work.

The length of the rapid traverse movement may be varied by adjusting theset screw 52 which is threaded in the end of cylinder 39 and locked inposition by a locking nut 53. Normally, once this adjustment has beenmade it would not be necessary to change it. The length of the rapidtraverse movement should, of course, be so adjusted as to permitsufflcient clearance between the wheel and the work when the wheel headis in its extreme rear position to permit loading and unloading of thework without danger of hitting the wheel,

The control circuit shown in Figures 5 and 6 are for governing thesemovements automatically and sequentially whereby the grinding wheel willexecute a complete automatic cycle of rapid traversing and feeding in tothe required size and returning after the grinding operation has beencompleted. This cycle is initiated by the operator who throws a lever toa starting position after which the cycle is executed and the leverautomaticaly returned to its stop position.

This cycle control lever is indicated by the reference numeral 54 inFigure 1 where it is shown mounted on the right hand side of themachine. This lever is connected to the end of a valve plunger 55, acontrol portion of which is indicated by the reference numeral 56 inFigure 5. The valve is indicated generally by the reference numeral 51and is provided with a constant pressure port 58 which is suppliedthrough channel 59 from a pump which has an intake 6| for withdrawingoil from a reservoir 62. A relief valve 33 is connected to the outputchannel 59 of the pump for controlling the pressure therein. The valveis shown in a running position at which time the lever 54 assumes theposition indicated by the dot and dash line 64. In the stop position ofthe valve, the lever assumes the position indicated by the line 65, andthe vane 66 assumes a position in which the port 58 is connected to aport 61 and thereby through channel 68 to cylinder 49. This holds thewheel head in its retracted position as previously explained. Byrotation of the lever from the position 65 to the position 64, thepressure port 58 is connected to port 69 and thereby to channel 1.0 tostart the automatic infeed cycle.

The channel 10 has a branch connection H to port 12 of an infeed controlvalve 13 but the plunger 14 of this valve is normally held in a righthand position by a spring I and therefore the port I2 is closed. Thefluid in channel Il may continue, however, through the annular groove 16in the sleeve of the valve 13 to passage I! and port I8 of a reversingvalve 19.

The plunger 80 of this valve is normally held in the position shown toclose the port 18 by pressure from the pump 60 which is connected toport BI and thereby through annular groove 82, and radial port 83 to aninternal bore 84 which serves as a cylinder, the bore being closed by afixed piston rod 85.

The channel is also connected through a re sistance 86 to port 81 of afootstock control valve 88 whereby the fluid pressure enters the upperend of the valve and forces the plunger 89 downward against a spring 90.The fluid pressure entering the chamber 9| in the upper end of the valveis able to continue through port 92, after the plunger moves down, andthrough channel 93 to port 94 located in the right hand end of theinfeed control valve 13, and to pressure switch 95, operation of whichinitiates rotation of the machine headstock.

Shifting of the footstock valve plunger 89 also interconnects a pair ofports 99 and 97, the latter being connected by channel 98 to a tailstockcenter operating cylinder 99. Normally, the port '91 isconnected to thepressure port I99 by the annular groove IllI whereby pressure exists incylinder 99 to hold the tailstock center I02 in a retracted positionagainst the resistance of a spring I93. In other words. a piston I94responsive to the pressure in cylinder 99 actuates the tailstock centerthrough a pivoted crank which is rotatable about a fixed pivot I95. Theport 96 is connected to a return line Iill which leads to the reservoir62. A low pressure relief valve I98 is connected in this line tomaintain a very low pressure in the exhaust system and thereby insureagainst air getting into the operating system.

It should now be apparent that when the port 9'! is interconnected tothe port 96 that the spring I03 will shift the tailstock center intoengagement with a work piece and force the oil out of cylinder 99 intothe return channel. the shifting of the footstock valve causes automaticinsertion of the tailstock center into the end of the work and automaticstartin of the headstock which causes rotation of the work. At the sametime the valve 88 connects pressure to the infeed control valve I3,shifting the plunger M to the left as viewed in Figure 5. whereby theport l2 becomes interconnected with port I99.

This results in the admission of pressure to channel I I9 which has abranch connection to port I I I of a start and stop control valve I l2for the cam actuating piston H3 and a second branch connection to portII4 of the rapid traverse cylinder Therefore 38. The line I I0 isalsoconnected to the cylinder 38 through a parallel branch lineconnection I I 5 which has a check valve H6 serially arranged therein,the line H5 terminating. in a second port II'I located in the cylinder38. When the wheel head is in a retracted position the piston 40 coversthe port I I4 whereby the first admission of pressure to cylinder 38must be through the check valve II6 which is set to olier apredetermined resistance to flow whereby the full pump pressure does notenter the cylinder at the beginning of the movement.

This produces a regulated acceleration of the wheel head until it hasmoved a suflicient distance that the piston 40 uncovers the port II 4whereby the pressure gradually builds up to full pump pressure and thusa maximum rate of movement of the wheel head.

The fluid in cylinder 39 is forced out to reservoir by movement of thewheel head through a control valve structure carried by the wheel headand comprising a valve sleeve I I8 which is operatively connected to therack piston 28 by a pin I I9. The sleeve has an internal bore I20 inwhich is fitted a plunger rod I2I but the plunger rod is threaded at 522in a fixed part I23 of the wheel head and locked against movement by alock nut I24. I

The plunger has two spools I25 and I26 separated by an annular grooveI21. It should now be apparent that the rack piston 28 and the valvesleeve H8 remain stationary and the rest of the structure moves as aunit relative thereto.

The oil in escaping from the cylinder 39 passes through the passage I28,annular groove I29 and port I30 formed in the sleeve II8 to the annulargroove I21 in plunger I2I. The annular groove I21 interconnects the portI36 to port I3I which is drilled in the annular groove I32 of sleeve H8.The annular groove is in constant communication with the port I33 whichis the terminus of the channel 68. As the wheel head advances while thepiston 28 and the sleeve II8 remain stationary, the spool I26 on theplunger I2I advances to close port I30, thereby trapping the fluid incylinder 39 which serves to decelerate the wheel head a it reaches theend of its rapid traverse stroke. The exhaust fluid flows throughchannel 68, interconnected ports 61 and I34 of the start and stop valve51, and return channel I35 to reservoir 62 through the low pressurerelief valve I08.

The channel I I0 which was connected to pressure by valve I3 has abranch connection to port II I of valve II2 as previously mentioned andurges the plunger I36 downwardly as viewed in Figure 5 simultaneouslywith the rapid traverse movement. This downward movement is retarded,however, by the enlarged piston I31 which operates against the backpressure in line I35. The object of this is to retard the movement ofvalve plunger I36 until the wheel head has completed its rapid traversemovement, at which time the pressure in channel I ID will rise andthereby shift the plunger I36 faster to connect the pressure port I38 toport I39 and thereby through channel I40 to port MI located in the endof cyl- .inder I42.

The cylinder I42 contains the previously mentioned piston I I3 whichactuates the feed rate control cam 45. The piston is connected foroperation of the cam in the following manner. Rack teeth I42 are formedlongitudinally of the piston and in mesh with pinion I43 for driving theslide I44 which has similarly formed rack teeth I45 engaging the gearI43, Figures 5 and 8.

As viewed in Figure 5, the piston II3'in'm'oving in the direction ofarrow II3, causing the slide I44 and cam 45 to move in the direction ofarrow SI and the cam face 45, i so inclined as to cause imovement of thefollower I45 to the right, thereis connected by annular groove I48 toport I49 and channel I50 which leads to a rate control valve ISI. Thisvalve has a rotatable plunger I52 in which is formed a spiral throttlinggroove I53 for variably throttling the flow from port I54 to port I55.The port I55 is connected to the return channel I01. The rate valveplunger I52 terminates in a manual control I56 which is located on thefront of the machine, as shown in Figure l, and a graduated dial I51 isassociated therewith to indicate the rate setting of the throttle valve.

The pinion I43 which transmits motion from the piston II3 to the cam 45is secured to a shaft I58 and this shaft has keyed thereto a crank armI59 in the end of which is an adjustable set screw I60 for engaging theend of a trip operated pilot valve plunger I6I which controls theshifting of the cycle reverse valve 19. This plunger has an enlargedcentral spool I62 and is normally held 'in the position shown by theconstant fluid pres sure in chamber I63- which is supplied by a branchchannel I64 from channel 68 in which a back pressure exists asdetermined by the relief valve The crank arm I59 is rotated in aclockwise direction by the pinion I43 simultaneously with the movementof the cam 45 and at the end of the cam stroke it engages the end of theplunger I6I shifting it to the right as viewed in Figure 5. A port I65which is constantly connected to a source of pressure acts on theenlarged spool I62 to complete the shifting of plunger I6I therebyhydraulically detenting it. The shifting of the plunger connects theport I65 to a port I66 and thereby through channel I61 to the tarryvalve I68.

This valve is of the same construction as the rate valve and has aspiral throttling groove I69 for controlling the rate of flow from portI to port I1I. The tarry valve is adjusted by a control knob I12 mountedon the front of the machine as shown in Figure 1 and provided with adial I13 to indicate the setting thereof. The port IN is connected by achannel I14 to port I located in the left end of the reverse valve 19.The object of the tarry valve is to delay the firing of the reversevalve plunger 80 a suflicient length of time to permit the grindingwheel to clean up the work, that is, to spark out. The pressure at portI 15 must rise to a sufficient degree to overcome the pump pressurewhich constantly exists in the interior cylinder 84. of the plunger 86as previously explained.

When this occurs the pressure port SI of valve 19 is connected byannular groove 82-to a port I16 and thereby through channel I11 to portI18 of a fluid operable mechanism for returning the manual control valveand its control lever 54 to a combined reverse and stop position. This:r'n'echanism comprises a pair of telescoping plungers I19 and I80 whichare constantly urged apart on which lnterengage the teeth onxa gear I84which is attached to the valve plunger "0f the valve 51.

Upon admission of pressure to port I18 the telescoping plungers move asa unit, thereby rotating the gear I83 and connected valve in acounterclockwise direction as viewed in Figure 5 and near the end of thestroke the plunger I19 uncovers a port I85 which is connected by channelI86 to an accumulator I81. The accumulator has a spring I88 which isadapted to yield under pressure whereby the plunger actuating fluid isadapted to expand into the accumulator and thereby momentarily reduceits pressure just as the valve reaches the end of its movement, therebyeasing the shock on the valve as it reaches a positive stop, limitingits movement.

This rotation of the valve positions the vane 56 midway between theports 58 and 69 whereby the pressure port 58 now becomes connected tothe port 61 so that fluid pressure immediately flows through channel 68to the rapid traverse piston.

At the same time the port 69 is interconnected to port I34 wherebychannel 10 becomes an exhaust line. The spring 15 actin on plunger 14 isof sufficient strength to immediately shift the plunger to the rightforcing the fluid through channel 93, valve 88 and resistance 86 tochannel 10. This immediately connects channel I II] to exhaust port I93,thereby providing for free ex.- haust of fluid from the rapid traversemotor.

Since th port I30 i closed by the spool I26 the fluid pressure enteringthe annular groove I32 is forced to go through the passage I89 and checkvalve I90 to cylinder 39, the check valve causing a pressure drop whichstarts the wheel head slowly until the spool I26 uncovers the port I30and opens up a bypass for the fluid around the check valve. The fluid inthe other end of the cylinder escapes through port II4 since check valveII6 cannot open and the wheel head will move back at a fast rate untilthe tapered end I9I of piston 40 throttles the escape of fluid throughport H4 and thereby causes deceleration of the wheel head until thepiston 40 hits the end of the cylinder 38.

During the rapid return of the wheel head, fluid is continually passingthrough the resistance 86, lowering the pressure in line 93 to a pointat which the headstock switch 95 will open. The spring 90 will thenstart to move the plunger 89 of the tailstock control valve until theport 91 becomes connected .to the pressure port I00 causing thetailstock center I 02 to be withdrawn from the work.

When the channel H0 is connected to exhaust by valve 13, it reduces thepressure in chamber I II of valve II2 whereby the constant back pressureacting in the cylinder I31 is enabled to shift the plunger I36 upward,thereby connecting the port I39 leading from the upper end of cylinderI42 to exhaust, and port I41 to pressure port I38 whereby actuatingfluid will enter the lower end of cylinder I42 and efiect returnmovement of piston I I3 and connected cam 45.

The cam 45 will effect axial movement of worm 33 against the pressure incylinder 36 and thereby additional retraction of the wheel head.

At the same time the counterclockwise rotation of the pinion I43 willcause counterclockwise rotation of the crank arm I59 and since constantpressure is now admitted to the cylinder I63 the plunger I6I will beshifted to the left, thereby disconnecting the pressure port I65 fromport I66. The latter port becomes connected to port I94 which isconnected to the back pressure reservoir line I35 and this maintains theline I61 full of fluid, thereby preventing the admittance of air whichmight affect the feed rate on the next operation. All the parts have nowreturned to 1 their starting position.

A brief summary of the sequence of events during an automatic infeedcycle is as follows. The throwing of the lever 54 to its start positionconnects fluid pressure to the rootstock valve causing the plungerthereof to move at such a rate that the footstock center will engage andpick up a work piece, it being understood that the work will normally beplaced upon a suitable work rest of proper height so that the center I02in moving forward will push the work on to the headstock center and atthe same time lift the work sufliciently to clear the work rest. Itshould be apparent that the work must be properly held between centersbefore anything else occurs. Having accomplished this, the tailstockcenter continues its movement and opens port 92 which thereby shifts theinfeed control valve plunger and operates the pressure switch 95 tostart the work rotating. The infeed control. valve connects pressure tothe rapid traverse motor which moves the wheelhead in and at the sametime connects pressure to the reversing valve for the feed rate controlmotor so that as soon as the rapid traverse movement is completed thefeeding movement may start.

The feed rate control piston II3 moves the cam 45 at a selected rate asdetermined by the setting of thecontrol valve I5I and by the time thefeeding movement is completed the cam 45 has moved out of engagementwith its follower, the worm shaft has engaged the positive stop 44 andthe crank arm I59, has tripped the pilot valve IGI. Fluid pressure isnow admitted by Way of channel I61 and tarry valve I68 to the reversingvalve 19 which eventually shifts to effect return of the control lever64 to its stop position. This results in port 69 being connected toreservoir and port 61 being connected to pressure whereby the rapidtraverse motor immediately starts return movement of the wheel head. Dueto the connection of port 69 to reservoir, pressure is immediatelyrelieved in the footstock valve as well as in the infeed control valveand the pressure switch 95 whereby the pressure switch goes off toimmediately stop rotation of the work and the infeed control valveplunger 14 shifts to the right to relieve the pressure in valve H2 sothat the plunger I36 can shift to connect the pressure port I38 to portI41 and thereby cause return movement of the feed rate piston II3. Thisproduces an additional return movement, in addition to the rapidtraverse movement, and the movement of the tailstock valve plunger istimed to be returned when these movements have ceased to withdraw thetailstock center from the work.

In addition to the mechanism for actually effecting the automatic infeedcycle, certain controls and interlocks have been provided whereby thismechanism may be utilized together with, or independent of, the tabletraversing mechanism. I

The power traversing of the table is controlled by the table start andstop valve which is operated by the lever 24, a reversing valve I95 anda pilot valve I96, Figure 6. The reversing valve I95 has a pressure portI91 to which the pump supply line 59 is connected, and a pair of motor.

ports I98 and I99 which are connected through the table control valve asshown in sections I8 and 20 thereof in Figure 6 to the motor lines 200and 20I respectively. In other words, the

table start and stop valve has a pair of ports 202 and 203 to which thelines 204 and 205 from ports I98 and I99 are connected, and when.the

valve plunger 23 is rotated clockwise to its start position, port 203 isconnected by groove 206 to port 201 and thereby line 20I, and port 202is connected by groove 208 to port 209 and thereby to line 200.

The reversing valve I has a plunger 2I0 in which is formed a pair ofannular grooves 2H and 2I2 for alternately connecting the pressure portto ports I98 and I99 respectively and for simultaneously connecting theremaining port to port 2I3 or 2I4, depending upon the direction of shiftof the plunger. These ports are alternately connected to a common returnline 2 I5 which leads to a feed rate throttle valve 2I6 by the plunger2I1 of the ilot valve I96 which also controls the shifting of thereversing valve plunger 2I0.

In other words, the ports 2 I3 and 2I4 are connected by channels 2I8 and2I9 to ports 220 and 22I of the pilot valve and the annular grooves 222and 223 in the pilot valve plunger are alternately positioned to connectthe ports 220 and 22I to the common exhaust port 224 to which the line2I5 is connected. The pilot valve also has a pair of pressure ports 225and 226 whereby as the plunger shifts and immediately after it passesthrough its center position it will connect a shot of pressure to theexhausting side of the table motor to assist in stopping it before thereversing valve is shifted.

The pilot valve has a pressure port 221 which is flanked by a pair ofports 228 and 229 which are connected by channels 230 and 23I to ports232 and 233 located in opposite ends of the reversing valve housing I95.The plunger 2I1 is provided with an enlarged spool 234 which is movablerelative to the pressure port 221 so that after passing the port a forcecomponent sufficient to complete the shifting of the plunger 2I1 isproduced. This acts in the nature of a hydraulic detenting mechanism. Acrank arm 235 is operatively connected'to the plunger for shifting thesame, the crank arm being keyed to the end of a trip shaft 236 whichcarries a trip lever 231 on the upper end thereof as shown in Figure 1for actuation by trip dogs 238 and 239 carried by the table I3.

It is desirable that a delayed reversing action be effected in the tableand to that. end each of the channels 230 and 23I have delay valves 240and MI serlally arranged therein. These valves operate to restrict thenow to the reversing valve but any return flow is by-passed around thesevalves by means or check valves 242 and 243 which are directionallyconnected to open under a return iiow from the reversing valve, butwhich will close upon a now to the reversing valve and thereby force thefluid to pass through the delay valves. The ports 228 and 229 arealternately connected to exhaust ports 244 and 245 which are connectedto the return line I01.

In addition to enecting shifting of the reversing V valve, the pilotvalve also functions to effect actuation of a power operable pick feedmechanism, indicated generally by the reference numeral 246 in Figure 5of the drawings. This mechanism comprises a reciprocable piston 241which is slidably mounted in a cylinder 248.

The opposite ends of the cylinder are connected by channels 249' and 250to a reversing valve 25L The reversing valve has a plunger 252, theshifting of which is controlled by the table pilot valve I96 byconnecting the end ports 253 and "254 to the pilot valve ports 228 and229 by channels 255 and 256. Each of the channels 255 and 256'has a pairof parallel connected check valves 251 and 258 but oppositely directedwhereby one valve *an armQSO-thatcarries a' pawl 28L The pawl 28lha's-aheel-282 which ls'a'dapted to engage an closes and the other opens upona flow to the 10 reversing valve, and vice versa upon a flow from thereversing valve. The channels 255 and 256 also conduct pressure forshifting the piston 241. With the parts in the position shown it will benoted that the pressure port 221 of the pilot valve is connected'tochannel 255 and this channel has branch connections to ports 259 and 269of the reversing valve. With the plunger 252 in the position shown theport 260 is connected by annular groove 26l to port 262 and thereby tochannel 259 whereby the fluid pressure'from port.

plunger 210 of this valve in the position shown the port 268is'conriec'ted by an annular groove 21| to port 212 and channel 249 tothe cylinder 248. The channel 249 has a resistance 213 serially arrangedtherein to retard operation of the piston 241 sufliciently to preventhammering.

It will now be apparent that upon shifting of the pilot valve, fluidpressure is immediately admitted to cylinder 248, causing actuation ofthe piston 241 and thereby operation of the pickfeed mechanism, thecheck valve'25'l functioning to retard the admittance of pressure toport 254 and thereby the shifting of the plunger '252' until the piston241 has completed its movement. When this occurs the p1un-ger'252completes its shift-' ing movement, closing port 263 but opening port264. This port then becomes'connected byway of annular groove 214 toport 215 and thereby to channel 259. This admits fluid pressure to theother end of cylinder 248 and returns the piston 241 to its startingposition. Therefore upon a single shifting movement of the pilot valveplunger the piston 241 is caused to execute a complete reciprocation.

The same eifect is produced when the pilot valve plunger 2 I 1 isshifted in the other direction, only the pressure is connected this timeto channel 255 and the plunger 252 is in position to connect port 259 toport 216 whereby the fluid will again flow to channel 261 and from'there on through the same path to the cylinder 248 shifting the pist0n241 to the left. While this is going on, pressure will be slowly leakingthrough the check valve 251 to shift the plunger '252 toward the rightand when the piston 241 reaclresth'e end of its stroke the pressurewillrise to complete the shifting movement. This will close the 'port'259and will interconnect port 269 to port 262 and rotation on-a shaft 219.The gea'ris integral'with' abutment 283 upon counterclockwise rotationof the arrn-280 and thus serves to'withdraw the pawl'from engagementwith the periphery of a ratchet wheel 284.

Upon clockwise rotation of the -arm='280 the pawl 28l will drop intoengagement with the ratchet wheel 284 and effect rotation of the shaft219. Theratchet wheel 284 has a gear'285 formed integral therewith andthis gear intermeshes with a gear 286 which is supported on a shaft 281and is adapted to be connected to'the shaft for rotation of the gearing41 and thereby of the worm 33.

The gear 286 carries means for stopping operation of the pick-feedmechanism which cornprises a button-288 which is so positioned that itwill engage the pointed end of the plunger 210 and shift'the same to theleft as viewed in Figure 5. The plunger'carries an enlarged spool 289 iwhich is movable relative to a pressure port 29!! whereby after thespool passes the pressure port the'admittance of pressure to the otherside of the spool will completethe shifting movement in the direction inwhich the plunger happens to be moving. This functions as a hydraulicdetent mechanism to hold the plunger in either one of its two positions.When the plunger'210 is shifted to theleft it closes the port 268 andinterconnects the port 212 with a'return port 29!.

The result of this is to stop the hydraulic impulses in line 261 frombeing communicated to the piston 241 and at the same time to connect thechannel 249 to the back pressure exhaust line whichmaintains sufficientfluid in channel 249 to prevent the entrance of air into the system.

It will beapparent that it is impossible to reset the plunger 210manually and therefore hydraulic means'are provided'for this purposeafter the 0 gear 286 has been rotated to remove the button 288' from thepath of the plunger.

nism comprises a resetvalve 292 which has a This mechapressure port293,'an exhaust port 294 and a "third port 295 which is connected bychannel 296 'to'port'291 located in' the left end of the valve Theplunger 296 is held in the position shown by a spring'299 and a shoulder300 formed on "the end of the plunger for engaging the end of thesleeve30!. "This positions the valve to conl'n'ect the port 295 to the exhaustport 294 whereby the plunger 210 may be shifted to the left withoutundue "resistance. When the plunger 298 is depressed, the 'p'ort'2 95 isconnected to the pressure port 293 which thereby'admits fluid pressureto -the port 291L's'hiftirig the plunger216 to the right. It will beunderstood that'after the pick feed mechanism has stopped operating thatthe table to both ends of the'cylinder 15. thereby equaliz- "mg thepressure on both ends of the piston and prises'a hand wheel 302 which isfixed to the end of a shaft'303 that carries a gear 304. The shaft "303is adapted to be axially'mo'ved in its bearings 305 and 36B wherebythegeai 306 may be engaged with a gear 301 for slow operation of thetable 13 or may be interengaged with internal gear teeth 338 of a gear303 to effect fast movement of the table. A spring pressed detent 310 isprovided for holding the shaft in either one of its two positions. Whenthe gear 364 is intermeshed with the gear 301 the drive is then througha train comprising a gear 31 l integral with the gear 33'1', gear 339,pinion 312, gear 313 and gear 314 which is integral therewith, and idler315 which is interposed between the gear 314 and a rack 31% which isattached to the underside of the table.

When the shaft 3133 is shifted to the right, the gear 3341 engages theinternal gear 308 in the manner of a clutch whereby the gear 309 isrotated directly by the shaft 303. Since the gear 312 is integrallyconnected to the gear 309 the drive is then through gear 313, pinion 314and idler M to the rack 313. The gears 313 and 314 are capable of axialmovement but are normally held in the position shown by a spring 3 I lwhich is interposed between them and extends into bores 318 and 319formed in the opposing faces thereof. A spacing rod 323 is mountedwithin the spring to limit the movement of the gear 313. The purpose ofthis construction is to shift gears 313 and 31 d to the left and therebydisengage the gear 313 from the gear 315 so that it is impossible toattempt to effect manual operation of the table while it is being powerdriven, or on the other hand to prevent rotation of the hand wheel 392during power actuation of the table.

The gear 3 it has an elongated hub 32! by which it is journaled in thebearing 322 and the hub has a reduced portion 323 which slides in abearing 32 5 and also extends into a chamber 325 to act as a piston forshifting the two gears, the gear 3M being pinned to the reduced portion323. The chamber 325 is connected by a channel 326 to port 321 of thetable start and stop control valve. When this valve is in the stopposition in which it is shown the port 321 is connected to an exhaustport 323 which thereby relieves the pressure in chamber 325 but when thevalve is rotated in a clockwise direction the pressure port 329 isconnected to the port 321 and thereby to the chamber 325. Thus, there isan interlock to disconnect the manual actuating mechanism from the worktable during power actuation thereof.

There is an additional interlock on the table start and stop controlvalve which prevents the starting of the table until the wheelhead hasbeen moved into engagement with the positive stop 44. This is aprecautionary measure to insure that all sizing of the work is done withthe wheelhead in engagement with the same stop. To this end the valveplunger 23 is provided with a locking notch 330 which is adapted to beengaged by a spring pressed locking plunger 331 which when in positionwill prevent clockwise rotation of the plunger 23 to a startingposition. The locking plunger is slidably mounted in a housing 332 andis normally held in position by a spring 333 located between anenlargement 334 on the plunger and the end of the housing. Theenlargement 334 being greater in diameter than the locking portion 331,serves to provide a dilferential area 335 which may serve as a piston toeffect withdrawal of the pin 331 against the resistance of the spring333. To this end the housing is provided with a port 336 to which isconnected a channel 33?, that is, a branch of the channel 140 thatsupplies the infeed piston 113 as shown in Figure '5. Therefore, whenthe infeed piston 113 is being actuated under pressure the locking pin331 is withdrawn so that the start and stop valve may be operated. Thepurpose of this is that during an infeed grinding operationit may bedesirable to effect a small reciprocation or oscillation of the workwith respect to the grinding wheel, especially in cases where the axiallength of the sur-- face being ground is a little greater than the widthof the grinding wheel.

For conventional reciprocating grinding opera tions the infeed ratevalve 152 is opened wide and the tarry valve 168 is closed with theresult that when the infeed start lever 53 is thrown to the startposition the rapid traverse piston and the infeed piston 113 movequickly to their end positions without delay whereby the positive stopis immediately engaged to insure a positive positioning of the grindingwheel.

, It should be noted that this operation also causes engagement of thetailstock center as well as the closing of the headstock switch whichproduces rotation of the work and since the interlock pin 331 has beenwithdrawn the operator may now throw the lever 24 to its start positionto cause reciprocation of the table. The wheel 15 is now rotated to movethe gringing wheel into engagement with the work and then the pick feedmechanism is set into operation t complete the grinding operation.

It should be noted that'the positive stop serves as the ultimate limitof movement of the grinding wheel during an infeed grinding operation,but during a reciprocating cycle it serves merely as a positive abutmentfrom which to start the infeeding of the grinding wheel.

When a reciprocating cycle has been completed the operator may move thegrinding wheel out of engagement with the work and simultaneously stopthe table by a single movement of the table control lever 24. This isaccomplished by moving the lever, not only t the stop position but to athird position previously referred to as the dash and dot line 26 shownin Figure 1. The effect of this is to rotate the valve plunger 23 asufficiently additional distance in a counterclockwise direction toconnect a pressure port 338 to port 339 in section 21 of the valve andthereby to channel 340which leads to port 115 of the reversing valve '19shown in Figure 5. The shifting of this valve as previously explained inconnection with the infeeding cycle, connects pressure to the channelIll which results in the throwing of the infeed cycle control lever 54to its stop position, thus causing immediate retraction of the grindingwheel.

When the wheel head is returned in this manner it can only be broughtback in again by operation of the infeed control level 54. It is to benoted that any time this lever is utilized to advance the wheel head andthe feed rate throttle valve 152 is set for a feed rate, that thethrottle valve may be by-passed to obtain a fast rate of movement bymerely throwing the lever beyond its normal infeed position. When thisis done a drilled passage 341 in the valve plunger interconnects port332 which is branch connected to line with exhaust groove 343 and port61 t the return line 135. This provides an open passage to reservoir,thereby momentarily eliminating the effect of the feed rate valve.

In addition to adjusting the feed rate by the throttle valve 152, majorchanges may be made in the rate'by changing'the angularity of the camwithout changing the setting of the throttle valve. Angularity changesare made more partie cularly, however, for changing the length of thefeed movement.

The means for changing the angularity of the cam is shown moreparticularly in Figures 7, 8 and 9. The cam 45 is mounted in a U-shapedholder 344 as shown in Figure 8. The holder bears against two rollers345. and 346 and is 'operatively connected to the rack I44 by a pin 341.The pin carries a block 348 which fits in a slot 349 formed in the backof the cam 45 for transmitting motion to the cam. The cam is backed upby two stops 350 and 35l and held against thestops by the hydraulicallyactuated follower roller I45. The stop 35l is keyed at 352 to anadjusting shaft 353.

The various sides of the hexagon are, different distances from thecenter beginning with the side 354 which is closest to center and whicheffects the smallest angularity of the cam. The distances of the sides355, 356, 351, 358 and 359 from the center increase by the sameincrement in the order named.

The shaft 353 has a knurled operating knob 360 whereby the stop 35! maybe rotatably adjusted to any one of six positions to obtain differentlengths of infeed for thesame length of movement of the cam.

A stop screw 36! limits the movement in one direction which is thefeeding movement whereby the cam always stops in the same position andwhich is such that the cam is just out of engagement with the followerroller so that the positive stop 44 shown in Figure 2' is alwayseffective.

The length of cam stroke is determined by an adjustable stop 362 shownin Figure 5 and having a threaded connection with the shaft 363 which isactuated through bevel gears 364 and 3.65 from the hand wheel 366mounted on the end of shaft 361 splined in gear 365. The shaft 363 has asplined connection with gear 364 so that a piston 368 On the end of theshaft sliding in cylinder 369 may act as a dashpot to cushion the shock.The cylinder is connected to pressure at all times.

Referring to Figure 4, the length of the infeed increments effected bythe pick feed mechanism may be varied by adjusting the stop 310longitudinally of the cylinder 248. The stop has an angular end 31!engaging the angular surface 312 on the threaded member 313. A threadedadjusting shaft 314 interengages therewith and has an operating knob315.

The shaft 314 has a gear reduction connection 316 to a graduated dial311. Thus, by rotating the knob 315, the stop is adjusted and the dialrotated simultaneously.

There has thus been provided an improved actuating and control mechanismfor a grinding machine which greatly improves the operation thereof, andwhich is highly selective whereby the various types of grindingoperations may be carried out automatically.

What is claimed is:

1. In a grinding machine having a fixedsupport, a work support and agrinding wheel suptransmitting movement to the grinding wheel support,said connection including a rack piston slidably mounted in the grindingwheel support, means to apply fluid pressure to said piston to effectrapid movement of the grinding wheel support, and means to move said camto effect a feeding movement of the grinding wheel support.

2. In a grinding machine having a fixed support, a work table and awheelhead mounted on said support for relative movement in angularlyrelated directions, a headstock and a tailstock carried by the tableincluding centers for supporting work for relative rotation with respectto the grinding wheel carried by the wheel head. the combination ofcontrol means for governing movement of the wheel head including a rapidtraverse piston and a feed piston,'a source of fluid pressure, a startand stop valve adapted said source of pressure to the rapid traversepising valve for connecting fluid pressure for shiftfeed piston forlmpartmg a slow rate of movegaging thev worm and operatively connectedfor when moved to a starting position to connect ton, fluid operablemeans for retracting the tailstock center, a tailstock control valvenormally in a position to connect said source of pressure to said fluidoperable means, means in the starting said tailstock control valve torelease the presslue on said tailstock center, resilient means foradvancing the tailstock center when pressure released, an infeed controlvalve fluid actuated upon shifting of the tailstock control valv forconnecting pressure to the rapid traverse piston, a reversing valve forthe feed piston adapted to be shifted by said pressure to initiateoperation of the feed piston, and means operable by the merit to thewheel head.

3. In a grinding machine having a work supporting table and a grindingwheel slide, the combination of a table motor, a rapid traverse motorand a feed motor for the wheel head, a source of fluid supply for all ofsaid motors, a first valve for connecting said source to the rapidtraverse motor to effect quick advance of the wheel head, additionalvalve means automatically operable to connect fluid to said feed motorto effect additional advance of the wheel head, means to regulate therate of movement of said feed motor to a slow rate for infeed grindingpurposes, or at a rapid rate for traverse grinding purposes, a thirdvalve for connecting said source of pressure to the table motor, meansnormally locking said third valve, and fluid operable means controlledby said additional valve means for releasing said locking means afterthe wheel head has completed its rapid traverse movement.

4. In a grinding machine having a fixed support, a work table slidablymounted on the support, and a wheel head slidably mounted on the supportfor movement toward and from the table, the combination of means foradvancing and retracting the wheel head relative to the table includinga cylinder formed in the wheel head, a piston slidably mounted in thecylinder, means in the fixed support for holding the piston againstmovement whereby the admission of pressure to either end of the cylinderwill cause movement of the wheel head, a valve member slidably mountedin the wheel head and operatively connected to said piston, portings inthe wheel head controlled by said valv member during advance of thewheel head to decelerate the wheel head, and bypass [check valveconnections paralleling said portings to initiate return movement at aprescribed accelerated rate.

5. In a grinding machine having a fixed support, a work table slidablymounted thereon, and a wheel head supported for movement toward and from'the work table, the combination of means for shifting the wheel headincluding a worm mounted in the fixed support for rotation and axialmovement, means operatively connecting the worm to the wheel head, meansfor holding the worm against axial movement including a cam mounted atone end of the worm and a hydraulic piston mounted at the other end ofthe worm for holding the same against the cam, means to move the cam ata prescribed rate to eflect axial shifting of the worm and therebyinfeeding of the Wheel head, and a fixed positive stop for ultimatelylimiting movement of the worm independent of the cam.

6. In a grinding machine having a fixed support, a work table slidablymounted thereon and a wheel head supported for movement toward and fromthe work table, the combination of means for shifting the wheel headincluding a worm mounted in the fixed support for rotation and axialmovement, means operatively connecting the Worm to the Wheel head, meansfor holding the worm against axial movement including a cam mounted atone end of the worm and a hydraulic piston mounted at the other end ofthe worm for holding the same against the cam, means to move the cam ata prescribed rate to efiect axial shifting of the worm and therebyinfeeding of the wheel head, fluid operable means for shifting said cam,and a throttle valve for said fluid operable means to determine the rateof cam movement.

7. In a grinding machine having :a fixed support, a work table slidablymounted thereon, and a wheel head supported for movement toward and fromthe Work table, the combination of means for shifting the Wheel headincluding a worm mounted in the fixed support for rotation and axialmovement, means operatively connecting the worm to the wheel head, meansfor holding the worm against axial movement including a cam at one endand a hydraulic piston at the other end of the worm, means to move thecam at a prescribed rate to effect axial shifting of the worm andthereby infeeding of the wheel head, a fixed positive stop forultimately limiting movement of the worm independent of the cam, andmeans to rotate said Worm to change the relative position of the wheelhead with respect to the actuating mechanism and thereby change the zoneof movement relative to the work.

8. In a grinding machine having a bed, a table and a grinding wheelsupport slidably mounted on the bed, and a grinding wheel rotatablymounted on the grinding wheel support, the combination of means foradvancing and retracting the wheel relative to the table for eitherinfeed or traverse grinding operations including a fluid operable motor,supply and return lines for the motor having a reversingvalve'interposed therein, fluid operable means for shifting said valveincluding a trip operated pilot valve, a delay valve interposed betweenthe pilot valve and reversing valve for delaying the shifting of thelatter, and means to close said delay valve for preventing operation ofthe reversing valve when the motor is utilized for advancing the wheelhead for traverse grinding operations.

9. In a grinding machine having a bed, a Work support mounted on the bedfor traverse movement, and a grinding wheel support, the combination ofmeans for advancing the grinding wheel support to and from the Worksupport including a fiuid operable motor, a fluid control circuit forsaid motor including a cycle control valve, manually operable means forpositioning said valve to initiate a cycle, a pilot valve, a cyclereversing valve and a motor reversing valve arranged in said circuit,means operable by the motor for shifting said pilot valve to effectshifting of the cycle reverse valve, and means responsive to shifting ofthe cycle reverse valve for shifting the motor reversing valve toreverse the actuation of said motor.

10. In a grinding machine having a Work supporting table and a grindingwheel support, the combination of a control circuit for controllingrelative movement between the supports including a table operated pilotvalve, a table reversing valve, a pick feed mechanism for the grindingwheel support including a reversing valve therefor, means controlled bythe pilot valve to efiect shifting of said table reversing valve, saidpick feed mechanism including a fluid operable piston, a cylindercontaining said piston, a pair of channels leading to opposite ends ofthe cylinder, a blocking valve in one of said channels, and means tripoperable by the pick feed mechanism for shifting said blocking valve tostop operation of the pick feed mechanism.

11. In a grinding machine having a work supporting table and agrindingwheel support, the combination of a control circuit forcontrolling relative movement between the supports, comprising a pickfeed mechanism for the grinding wheel support including a reversingvalve therefor, said pick feed mechanism including a fluid operablepiston, a cylinder containing said piston, a pair of channels leading toopposite ends of the cylinder, a blocking valve in one of said channels,means trip operable by the pick feed mechanism for shifting saidblocking valve to stop operation of the pick feed mechanism, a hydraulicdetent for holding said blocking valve in a stop position and fluidoperable means including a control valve for resetting said blockingvalve in running position.

12. In a machine tool having relatively movable work and tool supports,the combination of means for effecting a relative idling movementbetween said supports in a direction to bring the tool on the toolsupport into engagement with the work on the work support including aconstant stroke piston and cylinder mechanism, a manually operablecontrol valve for connecting pressure to said mechanism to cause saidmovement, a second piston operatively connected for shifting saidmechanism as a unit for causing additional movement of the support, acontrol cam opposing movement by said second piston and a fluid operablecontrol circuit for feeding said cam at a constant predetermined ratetocontrol the rate of movement imparted by said second piston.

13. In a machine tool having a work support and a tool support, thecombination of an inIeeding mechanism for causing a relative inieedingmovement between said supports including a constant stroke piston andcylinder mechanism, a manually operable control valve for connectingpressure thereto, a second piston for imparting additional movement at afeed rate including a reversing valve therefor normally held in oneposition, a cycle control valve remotely controlled by said manuallyoperated control valve for connecting pressure to shift said reversingvalve, and pilot control means trip operated by the secondnamed pistonto cause power actuation of said erse mechanism, and means forsubsequently and automatically connecting power to the feed mechanismand simultaneously to said interlocking means to effect release of theinterlock whereby the work support may be traversed during the feedingmovement of the grinding wheel support. a

'15. In a machine tool having movable work and tool supports, poweroperable means for moving one of said supports and other power operablemeans for moving the other of said supports,

thecombination with a control for starting and stopping thefirst-named-power operable means,

of an interlock normally positionable for holding the control in itsstop position, a second-control member shiftable for connecting power tosaid other power operable means and'simultaneously efiecting withdrawalof said interlock whereby onesupport may-be traversed during movement ofthe "other support.

16. In a grinding machine having a work support, a grinding wheelsupport and power operable means including a control lever for startingand stopping traversing of the work support, the combination with aninterlocking member normally positioned to hold the control lever in astop position, of a first fluid operable means for moving the grindingwheel support at a fast rate,

a second fluid operable means for controlling movement of the grindingwheel support at a feed rate, means for connecting fluid pressure tosaid first-named fluid operable means, a'control valve responsive to thefluid pressure connected to said first-named fluid operable means forconnecting fluid pressure to said second-named fluid operable means, afluid pressure actuator for releasing said interlocking member, saidcontrol valve also connecting fluid pressure for releasing saidinterlock.

17. In an infeed mechanism for the grinding wheel support of a grindingmachine having a pressure operated member operatively connected to thesupport for producing an infeeding movement thereof, the combination ofmeans for controlling the rate of operation of said movement including aslidable feed control cam, a cam follower. urged by said fluid pressureoperated member into engagement withsaid cam normal to its direction ofmovement thereof, a pivotal support for one end of said cam, anadjustable stop member engaging the other end of said cam for varyingthe angularity thereof about its pivot and thereby the length of feedingmovement effected for a given movement of the cam, and control poweroperable means for shifting the cam mechanism transversely to the axisof said follower.

JACOB DECKER.

ALBERT D. C. STUCKEY.

